This project is designed to establish estimates of the prevalence of auditory discriminatin difficulties in children with speech-, language-, and learning- disabilities. A sub-objectives is to determine whether the magnitude of their auditory discrimination problem is related to the severity of their communicative disorder. The second objective is to determine whether experimental training that emphasizes perception of relatively small acoustic differences will lead to improved auditory discrimination and to improved everyday communication. Testing and training will utilize and AX discrimination task, with tiral-by-trial feedback and reinforcement, and with "catch trials." (AX tasks were first employed by experimental psychologists and have been used in psychoacoustics and speech science.) Developmental age-related differences for normals on this task have already been demonstrated and preliminary research has shown aberrant performance on this task by children with speech articulation disorders and by young adults with long-standing learning disabilities. Furthermore, it has been demonstrated that performance on these tasks by young children and handicapped listeners is not contaminated by experimental artifacts such as response bias. Nevertheless, it should be emphasized that major interest is in the relative performance, on these tasks, of different groups of subjects. It is anticipated that the outcomes of this project will lead to development of new diagnostic and rehabilitative procedures for children seen in audiology, speech and language pathology, and learning disability clinics. Thus, the test procedures used will be designed to be amenable to future use by clinically-trained personnel.